Carbohydrates, also known as saccharides, are the dominant chemical constituents of the most abundant and dominant biomasses on earth, which comprise more than 60% of the total known plant mass. Common carbohydrates include sugars, starches, cellulose, and hemicelluloses, and their various chemical derivatives. Carbohydrates have the general chemical formula: Cm(H2O)n where the hydrogen and oxygen are in a ratio of 2:1 as for water (whence the name “hydrate of carbon”, since the constituents of water, hydrogen (H) and hydroxyl (OH), are bound to each carbon atom). Carbohydrates are neither chemical hydrates nor fatty acids; instead, they are polyhydroxyl-, aldehyde-, and ketone-containing compounds.
The carbohydrates are divided into four chemical groupings: monosaccharides, disaccharides, oligosaccharides, and polysaccharides. In general, the monosaccharides and disaccharides are commonly referred to as “sugars”. A common example of a monosaccharide is glucose, and common examples of disaccharides are sucrose and lactose. Oligosaccharides are chains of fewer than ten saccharides; polysaccharides are chains longer than ten saccharides. Biologically, polysaccharides serve for the storage of energy (e.g., starch and glycogen) and as structural support (e.g., cellulose and hemicellulose in plants and chitin in arthropods).
Cellulose has a formula of (C6H10O5)n. It is a polysaccharide consisting of a linear chain of several hundred to over ten thousand β(1→4) linked D-glucose units. Cellulose is the primary structural component of the cell wall of green plants, such as in many forms of algae and the oomycetes. Cellulose is both abundant and renewable. About 33% of all plant matter is cellulose, although the percentage may be higher in some plants, such as 90% in cotton and 40-50% in trees.
Another major carbohydrate is hemicellulose. Hemicellulose is a polysaccharide, consisting of various sugars. About 20% of all plant biomass is hemicellulose. As such, hemicellulose is both abundant and renewable.
Historically, harnessing this vast chemical resource has been done biologically, i.e., using microbes and other organisms to convert carbohydrates into other useful chemicals. In particular decarbonation of carbohydrates to make alcohol is traditionally accomplished by fermentation, such as by wine making and brewing beer. New technologies have emerged over the last several decades to convert carbohydrates or general biomass into other useful chemicals, especially hydrocarbons and related compounds, including liquid biodiesel, bioethanol, and bio-oils, using fermentation; dehydration, pyrolysis (including flash pyrolysis; see Bridgewater, “Principles and practice of biomass fast pyrolysis processes for liquids,” J. Anal. Appl. Phys. 51, 3-22 (1999) and Bartek (U.S. Pat. No. 8,236,173)); and gasification into to syngas (i.e., synthetic gas) by partial oxidation, followed by a Fischer Tropsch process to make hydrocarbons (see, e.g., Chronet, U.S. Pat. No. 8,137,655).
The ability to derive hydrocarbons and oxygenated hydrocarbons from carbohydrates could provide an important source of important chemical building blocks and fuels from renewable sources, especially during a time when the supply of geological hydrocarbons is increasingly uncertain. Nevertheless, despite all the advances with these traditional technologies, the production of hydrocarbons and oxygenated hydrocarbons from carbohydrate feedstocks is not efficient. Fermentation is a slow, sometimes inefficient process. Dehydration, pyrolysis, and gasification into a Fischer Tropsch process or bio-oils creates a large amount of char and other waste products (and thus wastes feedstock), and is energy intensive. As such, all the art standard techniques are unacceptable.
Therefore, it would be advantageous to develop new methods to produce hydrocarbons and oxygenated hydrocarbons from carbohydrates, such as sugars, cellulose and hemicellulose, without creating large amounts of char or other waste products or using large amounts of energy. Due to their high abundance and renewability, using carbohydrates as a feedstock could create a “green” solution to the world's energy and chemical needs. But there are a few problems associated with trying to use carbohydrates as precursors to fuels and chemicals. The present invention meets these and other needs.